Method of treating manganese-steel castings



Patented Aug. 28, 1923.

UNITED STAT ES PATENT OFFICE.

JOHN H. HALL AND MARSHALL F. APGAR, OF HIGH BRIDGE, NEW JERSEY, ASSIGNORS TO TAYLOR-WHARTON IRON AND STEEL COMPANY, OF HIGH BRIDGE, NEW JEE- SEY A CORP OBIATION OF NEW JERSEY.

METHOD OF TREATING MANGANESE-STEEL CASTINGS.

,No Drawing States, residing at High Bridge, in the county of Hunterdon and State -of New Jersey, have invented certain new and useful Improvements in Methods of TreatingManganese-Steel Castings, of which the following is a specification.

This invention provides an improved method of treating manganese steel castings -of large size and intricate section.

It may be said at the outset that we are aware of Walter Brintons Patent 812,811,

which discloses a method of preparatory treatment of manganese steel before the ult'. mate toughening treatment. It was the knowledge of and the practice of his invention that enabled us, after years of experi 40 mentation, to finally reach a definite conclusion as to the best method of treating large-v period according to the size and nature of and intricate castings. of manganese steel.

Manganese steel in the cast condition, and before treatment, is brittle and is characterized by its high co-eflicient of expansion and low thermal conductivity. Hence, in cooling, the heat is radiated so rapidly that the surface becomes cool whilethe interior is still hot. Contraction occurs contemporaneously with the cooling, which often results in cracked castings. Thiscondition also obtains with thick and thin sections of one and the same casting; and in heating up in the furnace similar conditions arise, and this is one of the faults of the Brinton method of treatment. a

In our method oftreating castings of lar size and intricate section, we remove t e casting from the mould while it is still at a red heat and place it in a furnace which is heated to substantially the temperature of the casting. We then seal the furnace, and when the casting andfurnace have a temperature in common, we slowly raise the. temperature of the casting to about 760 C.

and maintain that temperature for a comparatively long or short period accordin to the size and nature-of the casting. The temperature is then slowly reduced in order that all portions of the casting may be cooled at the same rate. When the casting has been brought to a emperature of about 300 C,

Application filed June 6, 1922. Serial No. 566,405.

.liminary annealing, by placing the casting,

while still red from the heat of casting, in a furnace having substantially the temperature of the casting, maintaining desirable control so as to establish a uniform temperature as between the casting and the furnace, gradually raising the temperature to about 760 C., and maintaining such tem perature for a comparatively long or short the casting.

2. The method of treating manganese steel castings of large size and intricate form,

which consists in subjecting them to a preliminary annealing, by placing the casting, while still red from the heat of the casting, in a furnace having substantially the temperature of the casting, maintaining desirable control so as to establish a uniform temperature as between the furnace and the casting, gradually raising'the temperature to the' requisite maximum annealing, temperature, maintaining such temperature for a period determined by the size and nature of the casting, and then slowly reducing the temperature so as to effect the cooling of all portions of the casting at a uniformly slow and regulated rate.

3. The method of treating manganese steel castings of large size and intricate form, which consists in subjecting them toa preliminary annealing, by lacing the casting, while still red from the eat of the casting, in a furnace having substantially the temperature of the casting, maintaining desirable control so as to establish a uniform temperature as between the furnace and the casting, gradually raising the temperature to the requisite maximum annealing tema period determined by the size and nature of the casting, gradually reducing the temperature to about 300 (3., and then proceeding in the usual way for the ultimate toughening treatment.

g 4:- llhe method of treating manganese steel castings of large size and intricate form, which consists in subjecting them to a preliminary annealing by placing the casting, while still red from the heat of the casting, in a furnace having substantially the temperature of the casting, maintaining desirable control so as to establish a uniform temperature as between the furnace and the casting, gradually raising the temperature to about 7 60 (3., holding such temperature for a period determined by the size and nature of the casting, gradually reducing the temperature so as toefl'ect the cooling of all portions of the casting at a uniformly slow and regulated rate, and then proceeding in the usual way. I

5. The method of treating manganese steel castings of large size and intricate form, which consists in placing the casting, while still red from the heat of the casting, in a furnace having substantially the temperature of the casting, sealing the furnace and establishing a uniform temperature as between the furnace and the casting, gradually raising the temperature to about 760 '43., holding such temperature for a period determined by the size and nature of the casting, gradually reducing the temperature to about 300 (1, rapidly cleaning the casting,

and then proceeding in the usual way.

In testimony whereof we affix our signa- 

